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DOE OSTI2021

Stimulated Nucleation of Skyrmions in a Centrosymmetric Magnet

Understanding the dynamics of skyrmion nucleation and manipulation is important for applications in spintronic devices. In this contribution, the spin textures at magnetic domain-boundaries stimulated by application of in-plane magnetic fields in a centrosymmetric kagome ferromagnet, Fe 3 Sn 2 , with thickness gradient are investigated using Lorentz transmission electron microscopy. Switching of the in-plane magnetic field is shown to induce a reversible transformation from magnetic stripes to skyrmions, or vice versa, at the interface between differently oriented domains. Micromagnetic simulations combined with experiments reveal that the rotatable anisotropy and thickness dependence of the response to the external in-plane field are the critical factors for the skyrmion formation. In addition, it is shown that the helicity of skyrmions can also be controlled using this dynamic process. Finally, the results suggest that magnetic materials with rotatable anisotropy are potential skyrmionic systems and provides a different approach for nucleation and manipulation of skyrmions in spintronic devices.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

Characterizing the magnetic fields of nearby molecular clouds using submillimeter polarization observations

Of all the factors that influence star formation, magnetic fields are perhaps the least well understood. The goal of this paper is to characterize the 3D magnetic field properties of nearby molecular clouds through various methods of statistically analysing maps of polarized dust emission. Our study focuses on nine clouds, with data taken from the Planck Sky Survey as well as data from the Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry observations of Vela C. We compare the distributions of polarization fraction (p), dispersion in polarization angles ($\mathcal {S}$), and hydrogen column density (N H ) for each of our targeted clouds. To broaden the scope of our analysis, we compare the distributions of our clouds’ polarization observables with measurements from synthetic polarization maps generated from numerical simulations. We also use the distribution of polarization fraction measurements to estimate the inclination angle of each cloud’s cloud-scale magnetic field. We obtain a range of inclination angles associated with our clouds, varying from 16° to 69°. We establish inverse correlations between p and both $\mathcal {S}$ and NH in almost every cloud, but we are unable to establish a statistically robust $\mathcal {S}$ versus NH trend. By comparing the results of these different statistical analysis techniques, we are able to propose a more comprehensive view of each cloud’s 3D magnetic field properties. These detailed cloud analyses will be useful in the continued studies of cloud-scale magnetic fields and the ways in which they affect star formation within these molecular clouds.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2022

Altered properties and structures of root exudate polysaccharides in a root hairless mutant of barley

Root exudates and rhizosheaths of attached soil are important features of growing roots. To elucidate factors involved in rhizosheath formation, wild-type (WT) barley (Hordeum vulgare L. cv. Pallas) and a root hairless mutant, bald root barley (brb), were investigated with a combination of physiological, biochemical, and immunochemical assays. When grown in soil, WT barley roots bound ~5-fold more soil than brb per unit root length. High molecular weight (HMW) polysaccharide exudates of brb roots had less soil-binding capacity than those of WT root exudates. Carbohydrate and glycan monoclonal antibody analyses of HMW polysaccharide exudates indicated differing glycan profiles. Relative to WT plants, root exudates of brb had reduced signals for arabinogalactan-protein (AGP), extensin, and heteroxylan epitopes. In contrast, the root exudate of 2-week-old brb plants contained ~25-fold more detectable xyloglucan epitope relative to WT. Root system immunoprints confirmed the higher levels of release of the xyloglucan epitope from brb root apices and root axes relative to WT. Epitope detection with anion-exchange chromatography indicated that the increased detection of xyloglucan in brb exudates was due to enhanced abundance of a neutral polymer. Conversely, brb root exudates contained decreased amounts of an acidic polymer, with soil-binding properties, containing the xyloglucan epitope and glycoprotein and heteroxylan epitopes relative to WT. We, therefore, propose that, in addition to physically structuring soil particles, root hairs facilitate rhizosheath formation by releasing a soil-binding polysaccharide complex.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2020

Enhanced X-ray diffraction of in vivo-grown μNS crystals by viscous jets at XFELs

μNS is a 70 kDa major nonstructural protein of avian reoviruses, which cause significant economic losses in the poultry industry. They replicate inside viral factories in host cells, and the μNS protein has been suggested to be the minimal viral factor required for factory formation. Thus, determining the structure of μNS is of great importance for understanding its role in viral infection. In the study presented here, a fragment consisting of residues 448–605 of μNS was expressed as an EGFP fusion protein in Sf9 insect cells. EGFP-μNS (448–605) crystallization in Sf9 cells was monitored and verified by several imaging techniques. Cells infected with the EGFP-μNS (448–605) baculovirus formed rod-shaped microcrystals (5–15 µm in length) which were reconstituted in high-viscosity media (LCP and agarose) and investigated by serial femtosecond X-ray diffraction using viscous jets at an X-ray free-electron laser (XFEL). The crystals diffracted to 4.5 Å resolution. A total of 4227 diffraction snapshots were successfully indexed into a hexagonal lattice with unit-cell parameters a = 109.29, b = 110.29, c = 324.97 Å. The final data set was merged and refined to 7.0 Å resolution. Preliminary electron-density maps were obtained. While more diffraction data are required to solve the structure of μNS (448–605) , the current experimental strategy, which couples high-viscosity crystal delivery at an XFEL with in cellulo crystallization, paves the way towards structure determination of the μNS protein.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2022

Effects of Water Contamination on Micropitting and Rolling Contact Fatigue of Bearing Steels

Abstract In this research, the effects of water contamination in oil were investigated on two kinds of failures that occur in bearing steel: micropitting and rolling contact fatigue. Whereas the presence of water in the oil had little effect on the generation of surface wear in these experiments, increases in the occurrences of micropitting and rolling contact fatigue were observed due to the presence of either dissolved or free water in lubricants. Additionally, the presence of white etching matter at crack interfaces was observed and evaluated. The experimental results showed that water content can be considered as a significant factor that accelerates the formation of micropitting and fatigue cracks in rolling bearings.

Engineering↗

DOE OSTI2020

Asphaltene-induced spontaneous emulsification: Effects of interfacial co-adsorption and viscoelasticity

Asphaltenes are a class of high molecular weight aromatic compounds found in crude oil. They adsorb onto toluene-water interfaces and induce a spontaneous emulsification phenomenon, whereby stable water-in-oil emulsions form without the need of an external energy input. This work aims to control and understand the factors affecting spontaneous droplet formation in the presence of asphaltene adsorption. This is particularly useful for crude oil refining, where the presence of a stable emulsion hampers the efficiency of downstream processing operations. We explore the effect of the addition of copolymers designed as crude oil flow improvers as a means to control the extent of emulsion formation. We find that the polymers competitively adsorb onto the toluene-water interface and diminish spontaneous emulsification. Additionally, we conduct fluorescence microscopy experiments and measurements of the interfacial energy to determine the mechanism of spontaneous emulsification in asphaltene systems. We conclude that an emulsion forms via the diffusion of molecular water into the oil phase and subsequent binding with asphaltene aggregates, leading to the nucleation of micrometer-sized water droplets. We find that the polymer forms complexes with the dissolved asphaltenes, possibly hampering the ability of diffused water to bind to the asphaltenes and reducing the extent of spontaneous emulsification. Finally, we investigate the role of interfacial shear and dilatational viscoelasticity to better understand which fundamental interfacial properties are important in the emulsification of asphaltene-laden systems. We find that the rate of formation of an interfacial microstructural network is inversely correlated with the extent and rate of spontaneous emulsification.

42 ENGINEERING↗

DOE OSTI2024

CO2 Saline Storage: Costs and Storage Capacity

This document provides a brief description of the current state of CO2 saline storage. It then discusses factors determining the cost of storage and provides examples for two storage formations. It concludes by discussing the factors influencing CO2 storage capacity and provides cost supply cirves for CO2 storage.

Morgan, David↗

DOE OSTI2024

Sustainable Aviation Fuel Combustion, Soot, and Contrail Formation

The aviation industry stands at a crossroads, facing the dual challenge of meeting the growing global demand for air travel while mitigating its environmental impact. As concerns over climate change intensify, sustainable aviation fuels (SAFs) have emerged as a promising solution to reduce the carbon footprint of air travel. The aviation sector has long been recognized as a contributor to greenhouse gas emissions, with carbon dioxide (CO 2 ) being a primary concern. SAFs, derived from renewable feedstocks such as biomass, waste oils, or synthetic processes, offer a promising avenue for reducing the net carbon emissions associated with aviation. While SAFs have shown potential in lowering CO 2 emissions, the combustion process introduces complexities related to soot particle formation and contrail generation that require comprehensive exploration. These aspects are pivotal not only for their environmental implications but also for their influence on atmospheric climate interactions. As the aviation industry increasingly embraces SAFs to meet sustainability goals, it is imperative to assess their combustion characteristics, unravel the mechanisms of soot formation, and scrutinize the factors influencing contrail development.

09 BIOMASS FUELS↗

DOE OSTI2024

Critical Review of LPBF Metal Print Defects Detection: Roles of Selective Sensing Technology

The integrative potential of LPBF-printed parts for various innovative applications depends upon the robustness and infallibility of the part quality. Eliminating or sufficiently reducing factors contributing to the formation of defects is an integral step to achieving satisfiable part quality. Significant research efforts have been conducted to understand and quantify the triggers and origins of LPBF defects by investigating the material properties and process parameters for LPBF-printed geometries using various sensing technologies and techniques. Frequently, combinations of sensing techniques are applied to deepen the understanding of the investigated phenomena. The main objectives of this review are to cover the roles of selective sensing technologies by (1) providing a summary of LPBF metal print defects and their corresponding causes, (2) informing readers of the vast number and types of technologies and methodologies available to detect defects in LPBF-printed parts, and (3) equipping readers with publications geared towards defect detection using combinations of sensing technologies. Due to the large pool of developed sensing technology in the last few years for LPBF-printed parts that may be designed for targeting a specific defect in metal alloys, the article herein focuses on sensing technology that is common and applicable to most common defects and has been utilized in characterization for an extended period with proven efficiency and applicability to LPBF metal parts defect detection.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Opposite polarity programs regulate asymmetric subsidiary cell divisions in grasses

Grass stomata recruit lateral subsidiary cells (SCs), which are key to the unique stomatal morphology and the efficient plant-atmosphere gas exchange in grasses. Subsidiary mother cells (SMCs) strongly polarise before an asymmetric division forms a SC. Yet apart from a proximal polarity module that includes PANGLOSS1 (PAN1) and guides nuclear migration, little is known regarding the developmental processes that form SCs. Here, we used comparative transcriptomics of developing wild-type and SC-less bdmute leaves in the genetic model grass Brachypodium distachyon to identify novel factors involved in SC formation. This approach revealed BdPOLAR, which forms a novel, distal polarity domain in SMCs that is opposite to the proximal PAN1 domain. Both polarity domains are required for the formative SC division yet exhibit various roles in guiding pre-mitotic nuclear migration and SMC division plane orientation, respectively. Nonetheless, the domains are linked as the proximal domain controls polarisation of the distal domain. In summary, we identified two opposing polarity domains that coordinate the SC division, a process crucial for grass stomatal physiology.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2024

PagMYB128 RNA-seq

PagMYB128 RNA-seq contains WT, SRDX and OE plants xylem RNA.

cellulose↗

NASA NTRS1973

International Symposium on Remote Sensing of Environment, 8th, University of Michigan, Ann Arbor, Mich., October 2-6, 1972, Proceedings. Volumes 1 & 2.

Recent developments in remote sensing techniques and applications are described in papers dealing with (1) ground-based, airborne, and space-borne sensor systems, (2) machine assisted data analysis and interpretation, and (3) specific uses of sensing techniques by various government units. Topics covered include monitoring of environmental quality factors, delineation of geological formations and mineral deposits, watershed management, observation of vegetative parameters in forestry and agriculture, design and performance details of various sensor systems and equipment, interpretation of multispectral imagery, and applications of ERTS-1 satellite imagery in resource study programs. Individual items are announced in this issue.

Source record↗

NASA NTRS1979

Warm/cold cloud processes

Technical assistance continued in support of the Atmospheric Cloud Physics Laboratory is discussed. A study of factors affecting warm cloud formation showed that the time of formation during an arbitrary expansion is independent of carrier gas composition for ideal gases and independent of aerosol concentration for low concentrations of very small aerosols. Equipment and procedures for gravimetric evaluation of a precision saturator were laboratory tested. A numerical feasibility study was conducted for the stable levitation of charged solution droplets by an electric field in a one-g static diffusion chamber. The concept, operating principles, applications, limits, and sensitivity of the levitation technique are discussed.

Bowdle, D. A.↗

NASA NTRS1984

Multi-image photometric solutions for the Galilean satellites

A method for determining the limb darkening planet, acquired in the same wavelength range (lambda), within a few degrees of the same phase angle (alpha), but acquired at different illumination and viewing conditions. The two images are first geometrically registered in simple cylindrical format. A limb darkening factor is computed for each pixel pair and output as a digital image. Systematic trends with photometric coordinates across this image indicate either a calibration error or inappropriateness of the particular photometric function. This method can be used for any photometric function with a single limb darkening factor, such as the Minnaert function or the function which combines the Lommel-Seeliger and Lambert functions. By solving for many pairs of images, the limb darkening factor as a function of alpha and lambda may be determined. The two image limb darkening solutions determined for 1 Voyager image pair on Ganymede, 16 image pairs on Callisto, 44 pairs on Europa, and 19 pairs on Io are discussed.

Mcewen, A. S.↗

NASA NTRS1984

The Effect of Growth Rate on Interface Morphology

Since significantly different solidification structures of a given alloy can be obtained by varying experimental growth rates, it is desirable to understand the basic factors which control the formation and stability of these microstructures when conditions are altered. Directional solidification experiments are described and the results obtained in metallic and transparent organic systems are presented. Emphasis is on the characteristics of dendritic structures obtained under different solidification conditions. Specifically, the effect of the growth rate on the primary dendritic spacing, the secondary dendrite spacing, and the dendrite tip radius is discussed. It is shown that significant changes in the primary spacing are observed when a dendrite to cellular transition takes place at lower velocities. It is found that the primary cellular spacing is much smaller than the primary dendrite spacing so that a maximum in the primary spacing occurs as a function of velocity at the dendrite-cellular transition. A theoretical model is also described which quantitatively explains various microstructural features of dendritic and cellular structures.

Trivedi, R.↗

NASA NTRS1985

Diagnosis of vertical motions from VAS retrievals during a convective outbreak

GOES-VAS satellite retrievals are used to investigate an intense convective outbreak over the Mississippi River Valley on 21-22 July 1982. The primary goals are to assess the strengths and weaknesses of three methods for computing vertical motion using satellite retrievals and to determine the effects of short interval observations on the calculations. Then, the vertical motions are incorporated with thermodynamic parameters to assess the usefulness of VAS data in delineating factors leading to storm formation. Results indicate that the quasi-geotrophic omega equation provided patterns and magnitudes most consistent with observed weather events and the 12 h radiosonde-derived motions. The vorticity method generally produced reasonable patterns, especially over the convective outbreak, although magnitudes were large due to its time derivative.

Funk, T. W.↗

NASA NTRS1988

Dinosaur bone beds and mass mortality: Implications for the K-T extinction

Mass accumulations of fossilized large terrestrial vertebrate skeletons (bone beds: BB) provide a test for K-T catastrophic extinction hypotheses. The two major factors contributing to BB formation are mode of death and sedimentation rate. Catastrophic mass mortality (CMM) is the sudden death of numerous individuals where species, age, health, gender, or social ranking offer no survivorship advantage. Noncatastrophic mass mortality (NCMM) occurs over time and is strongly influenced by species, age, or gender. In addition to cause of death, sedimentation rate is also important in BB formation. Models of BBs can be made. The CMM drops all individuals in their tracks, therefore, the BB should reflect the living population with respect to species, age, or gender. The NCMM results in monospecific BBs skewed in the direction of the less fit, usually the very young or very old, or towards a specific gender. The NCMM and AM BBs may become more similar the more spread out over time NCMM deaths occur because carcasses are widely scattered requiring hydraulic accumulation, and the greater time allows for more disarticulation and weathering. The CMM and NCMM BB appear to be dominated by social animals. Applying this and the characteristics of mortality patterns to the uppermost Cretaceous Hell Creek Formation indicates that only NCMM and AM BB occur. Furthermore, NCMM BB are rare in the upper third of the Hell Creek. Near the K-T boundary, only AM BB are known. The absence of CMM and NCMM BB appears to be real reflecting a decrease in population levels of some dinosaurs prior to the K-T event. The absence of CMM suggests that the K-T event did not lead to an instantaneous extinction of dinosaurs. Nor was there a protracted die-off due to an asteroid impact winter, because no NCMM BB are known at or near the K-T boundary.

Carpenter, Kenneth↗

NASA NTRS1988

Lightning and precipitation history of a microburst-producing storm

Quantitative measurements of the lightning and precipitation life cycle of a microburst-producing storm are discussed. The storm, which occurred on July 20, 1986 at Huntsville, Alabama, was studied using Doppler radar data. The storm produced 116 flashes, 6 of which were discharges to the ground. It is suggested that an abrupt decrease in the total flash rates is associated with storm collapse, and serves as a precursor to the arrival of the maximum microburst outflows at the surface. Ice-phase precipitation is shown to be an important factor in both the formation of the strong downdraft and the electrification of the storm.

Goodman, Steven J.↗